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The larval stages of the moths commonly called porina
moths (after the earlier generic name Porina) are
important pasture pests in New Zealand. They live in tunnels
in the soil during the day and feed at night at the surface
of the soil on grass foliage. The damage done by them to
pastures is comparable to that caused by the grass grub. Like
the grass grubs, the subterranean grass caterpillars have
adapted themselves very successfully to the introduced
grasses which now dominate the grasslands of New Zealand. The
life cycle is an annual one. Eggs are deposited on grasses in
October to January, and the caterpillars are active from
December to September. Adults appear in October to January.
They do not damage plants but are attracted to light in great
numbers and, in the South Island particularly, are a
predominant feature of the insect life of early summer.
Control is successfully carried out by the application of
insecticides to the pastures. Many species of grass
caterpillars are known, but only two or three are of
importance as pasture pests. Other species are particularly
prone to attack by the fungus Cordyceps. The
caterpillars are attacked in the ground and, when all the
caterpillar tissue is replaced by the fungus, a spore-bearing
stalk is produced and protrudes above the ground. In this
state the organism is called a vegetable caterpillar.

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How to cite this page: 'CATERPILLAR, SUBTERRANEAN GRASS', from An Encyclopaedia of New Zealand, edited by A. H. McLintock, originally published in 1966.Te Ara - the Encyclopedia of New ZealandURL: http://www.TeAra.govt.nz/en/1966/caterpillar-subterranean-grass (accessed 26 May 2019)